1. Field of the Invention
The present invention relates to an imaging module and an imaging device, and particularly, to an imaging module and an imaging device capable of simultaneously capturing a plurality of images having different characteristics.
2. Description of the Related Art
Conventionally, an imaging device that comprises an imaging optical system 1 including a central optical system (a wide-angle lens) 1a in a central portion and an annular optical system (telescopic lens) 1b in a portion surrounding the central optical system having different characteristics from the central optical system 1a, which are arranged on the same optical axis, an image sensor 3, and an array lens 2 including a plurality of microlenses (pupil imaging lenses) arranged on the incidence surface side of the image sensor 3, which forms a pupil image of the imaging optical system on the image sensor 3 using each microlens, as illustrated in FIG. 20, has been proposed (JP2012-253670A).
An image plane of the imaging optical system 1 is on the array lens 2, and the array lens 2 forms a pupil image of the imaging optical system 1 on the image sensor 3.
FIG. 21 illustrates one light reception cell 3a on the image sensor 3, and the pupil image of the imaging optical system 1 that one microlens of the array lens 2 forms on the image sensor 3. This pupil image includes a central pupil image (wide-angle lens component) corresponding to the central optical system 1a, and an annular pupil image (telescopic lens component) corresponding to the annular optical system 1b. 
Portion (a) of FIG. 22 illustrates an example in which 5×5 light reception cells 3a of the image sensor 3 are assigned per microlens.
As illustrated in portion (a) of FIG. 22, in every group of 5×5 (=25) light reception cells, a central pupil image (wide-angle lens component) is received by the light reception cell in the central portion, and an annular pupil image (telescopic lens component) is received by the light reception cells in the surrounding portion.
In every group of 25 light reception cells, an image signal of one pixel of a wide-angle image is generated from the light reception cell receiving a wide-angle lens component and, similarly, an image signal of one pixel of a telescopic image is generated from the light reception cell receiving a telescopic lens component. Accordingly, a wide-angle image corresponding to the wide-angle lens and a telescopic image corresponding to the telescopic lens are obtained, as illustrated in portion (b) and portion (c) of FIG. 22.
In the example illustrated in FIG. 22, a relationship between the number of light reception cells of the image sensor 3 and the number of pixels of the wide-angle image and the telescopic image obtained from the image sensor 3 is the number of light reception cells:the number of pixels (×the number of images)=25:1 (×2).
When the 5×5 light reception cells 3a of the image sensor 3 are assigned to each microlens as illustrated in FIG. 22, there is a problem in that the number of pixels of images (a wide-angle image and a telescopic image in the above example) having different characteristics obtained from the image sensor 3 is greatly decreased as compared to the number of light reception cells of the image sensor 3.
A simplest method of suppressing a decrease in the number of pixels of the images having different characteristics obtained from the image sensor 3 is to reduce the number (assignment number) of light reception cells assigned to each microlens. It is possible to increase the number of pixels of images having different characteristics that can be taken out, by an amount corresponding to a reduction in the assignment number.
Portion (a) and portion (b) of FIG. 23 illustrate an example in which 5×5 light reception cells 3a of the image sensor 3 are assigned to each microlens, and an example in which 3×3 light reception cells 3a are assigned, respectively.
That is, in a case in which the imaging optical system is concentrically divided, the assignment number of the reception cells that can be assigned to each microlens of the array lens is limited to 3×3. In this case, a relationship between the number of light reception cells of the image sensor 3 and the number of pixels of a wide-angle image or a telescopic image obtained from the image sensor 3 is the number of light reception cells:the number of pixels=9:1.
In JP2012-253670A, there is a description that color filters are arranged in a light reception element in a predetermined pattern in order to capture a color image, but there is no description of a specific color filter array.
Meanwhile, in JP2013-90059A and JP2013-115532A, an imaging device that uses a general imaging lens and an array lens (microlens array) arranged on the incidence surface side of the image sensor, and acquires a pixel signal based on the amount of received light by causing rays to be incident on each light reception cell of the image sensor while dividing rays passing through the imaging lens into rays from a plurality of viewpoints using the lens array is described.
In JP2013-90059A and JP2013-115532A, there is a description that rays passing through one microlens are received by the 3×3 light reception cells, and there is a description that color filters in a Bayer array are provided on the image sensor, and the color filter of one of red (R), green (G), and blue (B) is provided in each light reception cell.
Nine viewpoint images can be generated by extracting an output signal of the light reception cell in the same position from the 3×3 light reception cells corresponding to each microlens and reconstructing the image, but the viewpoint image generated in this way becomes a color image (mosaic image) of a Bayer array (see FIG. 11 in JP2013-90059A).
An example of pupil division device may include a device that causes a light beam passing through respective areas having different characteristics of a multi-lens to be incident on different reception cells by a microlens provided in each light reception cell and a light shielding mask (JP2012-253670A).